We propose to conduct and evaluate tuberculosis screening and directly observed preventive therapy efforts on populations of active drug users recruited a) at the time of admission to an inpatient detox facility and b) from participants of a needle exchange/HIV-risk reduction program. I) We will determine the prevalence of latent and active TB and anergy. We will analyze the sociodemographic, clinical and drug use variables associated with TB status and anergy. We will also examine the relative utility of various screening maneuvers for the detection of active and latent TB among active drug users in a high TB and HIV prevalence area. II) We will link the screening efforts to the recruitment to and provision of directly observed preventive therapy (DOPT) for tuberculin positive and anergic active drug users. DOPT will generally consist of twice weekly isoniazid (15 mg/kg) provided a) within the context of an HIV-primary care clinic (for those recruited through inpatient detox) and b) at the time of needle exchange (for those recruited from and continuing to participate in the needle exchange/harm reduction program). We will evaluate the feasibility and acceptance of providing DOPT in these settings. III) We will evaluate DOPT with respect to a) factors associated with and predictive of failure to engage in treatment, retention in treatment and treatment completion, b) the utility of a health contract in promoting treatment adherence, c) and the long term efficacy among those enrolled in DOPT by cross-match with NYCDOH and NYSDOH TB registries.